diff options
| author | Johannes Berg <johannes.berg@intel.com> | 2017-04-11 12:10:58 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-04-11 10:54:27 -0400 |
| commit | 96a94cc5158859943b7e4e72ae69e572815f5413 (patch) | |
| tree | f0c49877450c2ac6c37b91ab930916a5c65752d0 /kernel | |
| parent | 17c3060b1701fc69daedb4c90be6325d3d9fca8e (diff) | |
| download | lwn-96a94cc5158859943b7e4e72ae69e572815f5413.tar.gz lwn-96a94cc5158859943b7e4e72ae69e572815f5413.zip | |
bpf: reference may_access_skb() from __bpf_prog_run()
It took me quite some time to figure out how this was linked,
so in order to save the next person the effort of finding it
add a comment in __bpf_prog_run() that indicates what exactly
determines that a program can access the ctx == skb.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/core.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index f45827e205d3..b4f1cb0c5ac7 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -1162,12 +1162,12 @@ out: LD_ABS_W: /* BPF_R0 = ntohl(*(u32 *) (skb->data + imm32)) */ off = IMM; load_word: - /* BPF_LD + BPD_ABS and BPF_LD + BPF_IND insns are - * only appearing in the programs where ctx == - * skb. All programs keep 'ctx' in regs[BPF_REG_CTX] - * == BPF_R6, bpf_convert_filter() saves it in BPF_R6, - * internal BPF verifier will check that BPF_R6 == - * ctx. + /* BPF_LD + BPD_ABS and BPF_LD + BPF_IND insns are only + * appearing in the programs where ctx == skb + * (see may_access_skb() in the verifier). All programs + * keep 'ctx' in regs[BPF_REG_CTX] == BPF_R6, + * bpf_convert_filter() saves it in BPF_R6, internal BPF + * verifier will check that BPF_R6 == ctx. * * BPF_ABS and BPF_IND are wrappers of function calls, * so they scratch BPF_R1-BPF_R5 registers, preserve |